/* Copyright (c) 2006-2010 by OpenLayers Contributors (see authors.txt for
* full list of contributors). Published under the Clear BSD license.
* See http://svn.openlayers.org/trunk/openlayers/license.txt for the
* full text of the license. */
/**
* @requires OpenLayers/Events.js
*/
/**
* Class: OpenLayers.Handler
* Base class to construct a higher-level handler for event sequences. All
* handlers have activate and deactivate methods. In addition, they have
* methods named like browser events. When a handler is activated, any
* additional methods named like a browser event is registered as a
* listener for the corresponding event. When a handler is deactivated,
* those same methods are unregistered as event listeners.
*
* Handlers also typically have a callbacks object with keys named like
* the abstracted events or event sequences that they are in charge of
* handling. The controls that wrap handlers define the methods that
* correspond to these abstract events - so instead of listening for
* individual browser events, they only listen for the abstract events
* defined by the handler.
*
* Handlers are created by controls, which ultimately have the responsibility
* of making changes to the the state of the application. Handlers
* themselves may make temporary changes, but in general are expected to
* return the application in the same state that they found it.
*/
OpenLayers.Handler = OpenLayers.Class({
/**
* Property: id
* {String}
*/
id: null,
/**
* APIProperty: control
* {<OpenLayers.Control>}. The control that initialized this handler. The
* control is assumed to have a valid map property - that map is used
* in the handler's own setMap method.
*/
control: null,
/**
* Property: map
* {<OpenLayers.Map>}
*/
map: null,
/**
* APIProperty: keyMask
* {Integer} Use bitwise operators and one or more of the OpenLayers.Handler
* constants to construct a keyMask. The keyMask is used by
* <checkModifiers>. If the keyMask matches the combination of keys
* down on an event, checkModifiers returns true.
*
* Example:
* (code)
* // handler only responds if the Shift key is down
* handler.keyMask = OpenLayers.Handler.MOD_SHIFT;
*
* // handler only responds if Ctrl-Shift is down
* handler.keyMask = OpenLayers.Handler.MOD_SHIFT |
* OpenLayers.Handler.MOD_CTRL;
* (end)
*/
keyMask: null,
/**
* Property: active
* {Boolean}
*/
active: false,
/**
* Property: evt
* {Event} This property references the last event handled by the handler.
* Note that this property is not part of the stable API. Use of the
* evt property should be restricted to controls in the library
* or other applications that are willing to update with changes to
* the OpenLayers code.
*/
evt: null,
/**
* Constructor: OpenLayers.Handler
* Construct a handler.
*
* Parameters:
* control - {<OpenLayers.Control>} The control that initialized this
* handler. The control is assumed to have a valid map property; that
* map is used in the handler's own setMap method. If a map property
* is present in the options argument it will be used instead.
* callbacks - {Object} An object whose properties correspond to abstracted
* events or sequences of browser events. The values for these
* properties are functions defined by the control that get called by
* the handler.
* options - {Object} An optional object whose properties will be set on
* the handler.
*/
initialize: function(control, callbacks, options) {
OpenLayers.Util.extend(this, options);
this.control = control;
this.callbacks = callbacks;
var map = this.map || control.map;
if (map) {
this.setMap(map);
}
this.id = OpenLayers.Util.createUniqueID(this.CLASS_NAME + "_");
},
/**
* Method: setMap
*/
setMap: function (map) {
this.map = map;
},
/**
* Method: checkModifiers
* Check the keyMask on the handler. If no <keyMask> is set, this always
* returns true. If a <keyMask> is set and it matches the combination
* of keys down on an event, this returns true.
*
* Returns:
* {Boolean} The keyMask matches the keys down on an event.
*/
checkModifiers: function (evt) {
if(this.keyMask == null) {
return true;
}
/* calculate the keyboard modifier mask for this event */
var keyModifiers =
(evt.shiftKey ? OpenLayers.Handler.MOD_SHIFT : 0) |
(evt.ctrlKey ? OpenLayers.Handler.MOD_CTRL : 0) |
(evt.altKey ? OpenLayers.Handler.MOD_ALT : 0);
/* if it differs from the handler object's key mask,
bail out of the event handler */
return (keyModifiers == this.keyMask);
},
/**
* APIMethod: activate
* Turn on the handler. Returns false if the handler was already active.
*
* Returns:
* {Boolean} The handler was activated.
*/
activate: function() {
if(this.active) {
return false;
}
// register for event handlers defined on this class.
var events = OpenLayers.Events.prototype.BROWSER_EVENTS;
for (var i=0, len=events.length; i<len; i++) {
if (this[events[i]]) {
this.register(events[i], this[events[i]]);
}
}
this.active = true;
return true;
},
/**
* APIMethod: deactivate
* Turn off the handler. Returns false if the handler was already inactive.
*
* Returns:
* {Boolean} The handler was deactivated.
*/
deactivate: function() {
if(!this.active) {
return false;
}
// unregister event handlers defined on this class.
var events = OpenLayers.Events.prototype.BROWSER_EVENTS;
for (var i=0, len=events.length; i<len; i++) {
if (this[events[i]]) {
this.unregister(events[i], this[events[i]]);
}
}
this.active = false;
return true;
},
/**
* Method: callback
* Trigger the control's named callback with the given arguments
*
* Parameters:
* name - {String} The key for the callback that is one of the properties
* of the handler's callbacks object.
* args - {Array(*)} An array of arguments (any type) with which to call
* the callback (defined by the control).
*/
callback: function (name, args) {
if (name && this.callbacks[name]) {
this.callbacks[name].apply(this.control, args);
}
},
/**
* Method: register
* register an event on the map
*/
register: function (name, method) {
// TODO: deal with registerPriority in 3.0
this.map.events.registerPriority(name, this, method);
this.map.events.registerPriority(name, this, this.setEvent);
},
/**
* Method: unregister
* unregister an event from the map
*/
unregister: function (name, method) {
this.map.events.unregister(name, this, method);
this.map.events.unregister(name, this, this.setEvent);
},
/**
* Method: setEvent
* With each registered browser event, the handler sets its own evt
* property. This property can be accessed by controls if needed
* to get more information about the event that the handler is
* processing.
*
* This allows modifier keys on the event to be checked (alt, shift,
* and ctrl cannot be checked with the keyboard handler). For a
* control to determine which modifier keys are associated with the
* event that a handler is currently processing, it should access
* (code)handler.evt.altKey || handler.evt.shiftKey ||
* handler.evt.ctrlKey(end).
*
* Parameters:
* evt - {Event} The browser event.
*/
setEvent: function(evt) {
this.evt = evt;
return true;
},
/**
* Method: destroy
* Deconstruct the handler.
*/
destroy: function () {
// unregister event listeners
this.deactivate();
// eliminate circular references
this.control = this.map = null;
},
CLASS_NAME: "OpenLayers.Handler"
});
/**
* Constant: OpenLayers.Handler.MOD_NONE
* If set as the <keyMask>, <checkModifiers> returns false if any key is down.
*/
OpenLayers.Handler.MOD_NONE = 0;
/**
* Constant: OpenLayers.Handler.MOD_SHIFT
* If set as the <keyMask>, <checkModifiers> returns false if Shift is down.
*/
OpenLayers.Handler.MOD_SHIFT = 1;
/**
* Constant: OpenLayers.Handler.MOD_CTRL
* If set as the <keyMask>, <checkModifiers> returns false if Ctrl is down.
*/
OpenLayers.Handler.MOD_CTRL = 2;
/**
* Constant: OpenLayers.Handler.MOD_ALT
* If set as the <keyMask>, <checkModifiers> returns false if Alt is down.
*/
OpenLayers.Handler.MOD_ALT = 4;